The invention pertains to a foot prosthesis.
Many different types of foot prostheses are known. The goal of each foot prosthesis is to make the foot-fall as comfortable as possible, to cushion it on the basis of the elastic properties of the prosthesis, and to make it possible for the user to walk in a manner close to that in which one would walk with a real foot. One of the known foot prostheses comprises a lower part, which is set down on the ground when walking. Arranged on the lower part is an elastic damping element, which is arranged with an offset primarily toward the heel area. On this elongated damping element, a metal plate with a suitable fastening element such as a pyramid receiver is provided, on which a connecting shaft or the like, by which the entire prosthesis is attached to the leg stump, can be arranged. The damping element gives the plate a certain elastic mobility relative to the lower part. To achieve a certain pretension within the damping element, cable or strap loops are provided in front of and behind the connecting means, for example, the pyramid receiver, on the plate side; these loops pass over the plate, proceed to the lower part, and are either fastened to the lower part or pass under it. By this means the retaining plate is permanently connected to the lower part, i.e. put under tension with respect to it. These cable or strap connections are flexible to the extent that the retaining plate can move elastically toward the lower part, this being true both in the rear heel area and in the forward area located more-or-less in the middle of the foot. Nevertheless, the outward elastic movement and thus the relaxation of the damping element is limited by the cable or strap loops, so that the pretension remains in effect. This doubly limited movement ultimately results in a limitation of the mobility of the lower part relative to the plate. When the heel section is set down, inward deflection at the heel is possible, but the forward end, where the retaining plate is located, cannot follow, because its movement is limited by the cable or strap loop present there. As the foot rolls off at the tip, the retaining plate can deflect inward in the forward area relative to the lower part, but an outward deflection in the heel area is not possible, because the relative mobility is limited by the cable or strap connection present there. This means that there is only a limited ability to move around the actual center of rotation between the rear foot and the forefoot lever, i.e., between the retaining plate and the lower part, because the movement is limited in both directions.